Organic Light Emitting Diode (OLED) is a flat panel display technology which has great prospects for development. It does not only possess extremely excellent display performance but also properties of self-illumination, simple structure, ultra thin, fast response speed, wide view angle, low power consumption and capability of realizing flexible display, and therefore is considered as “dream display”. Meanwhile, the investment for the production equipments is far smaller than the Liquid Crystal Display (LCD). It has been favored by respective big display makers and has become the main selection of the third generation display element.
An OLED generally comprises: a substrate, a Hole Injection Layer (HIL) located on the substrate, a Hole Transport Layer (HTL) located on the Hole Injection Layer, a light emitting layer (Emitter) located on the Hole Transport Layer, an Electron Transport Layer (ETL) located on the light emitting layer, an Electron Injection Layer (EIL) located on the Electron Transport Layer and a Cathode located on the Electron Injection Layer. For promoting the efficiency, the light emitting layer is generally applied with co-host system. At present, there are several technologies of realizing the OLED colorization: one is Red, Green, Blue (RGB), three primary colors luminescence, represented by Samsung Corp. This technology is only applied for organic small molecular material which is easily sublimated. The merit is that the process is simple, mature and easy for operation. However, the high accuracy mask and the precise alignment are required as manufacturing the high resolution display panel, the production is inevitably lower and the manufacture cost is higher, accordingly. Besides, the differences of the lifetimes, the excitation rates and the decays of the three primary colors are large, which can likely result in the color cast of the OLED color display device.
Another is white light+RGB color filters (CF) technology, represented by LG Corp. The mature CF technology of the LCD can be utilized. No mask alignment is required, which tremendously simplifies the evaporation process to cut down the manufacture cost and to be applicable for manufacturing large scale high resolution OLED.
Nevertheless, in the white light+RGB color filters technology, the light emitting layer is not doped with electron transport material to make the light emitting position away from the interface of the light emitting layer and the Electron Transport layer. As a result, the energy efficiency is lower and the power consumption is higher.
Therefore, there is a need to develop an OLED display device, possessing higher energy efficiency and low power consumption.